What blocking your number actually does
When you block your number on an outgoing call, the person receiving it sees "Unknown," "Blocked," or "Private Number" instead of your phone number. Your call still goes through — they can still answer and hear you — but they cannot see who is calling them or call you back at that number later.
Blocking incoming calls is different: you stop calls from a specific number from reaching your phone at all. The caller hears a message (usually that the number is disconnected or unavailable), and the call does not appear in your phone's log.
These are two separate features. You can block your outgoing number without blocking any incoming calls, and you can block incoming calls without hiding your own number.
Key Takeaways
- Blocking your outgoing number on a single call uses *67 on most landlines and older phones, or a setting in your phone's dialer app on smartphones.
- Blocking incoming calls from a specific number is done through your phone's settings or your carrier's online account, and the blocked caller will not know they are blocked.
- Some calls cannot be blocked — emergency services, your carrier's own messages, and calls from people who pay to unblock caller ID will still reach you.
- If you block your number on every call, some businesses and government offices will not answer, because they screen out blocked calls.
How to block your number on a single call
On a landline or older phone: Dial *67 before the number you are calling. So if you want to call 555-0123, you dial *67-555-0123. The call goes through with your number hidden. This works on most carriers in the United States, though a few regional carriers use different codes — if *67 does not work, contact your carrier to ask what code they use.
On an iPhone: Open the Phone app, go to Settings (the gear icon at the bottom), tap Show My Caller ID, and turn it off. This hides your number on all calls you make until you turn it back on. If you want to hide it on just one call, there is no built-in option — you have to turn it off, make the call, and turn it back on.
On an Android phone: Open the Phone app, tap the three-line menu, go to Settings, then Call Settings, then Additional Settings, then Caller ID. Choose "Hide Number." Like iPhone, this applies to all your calls until you change it back. Some Android phones and carriers have different menu paths — if you cannot find these options, search your phone's settings for "caller ID" or contact your carrier.
How to block incoming calls from a specific number
On an iPhone: Open the Phone app, find the number in your recent calls or in a voicemail, swipe left on it (or tap the info icon), and select Block This Caller. You can also go to Settings, Phone, Blocked Contacts, and add numbers manually. Blocked callers will hear a message that the call cannot be completed.
On an Android phone: Open the Phone app, find the number in your call history, press and hold it, and tap Block Number. On some Android phones, you tap the info icon next to the number instead. You can also go to Settings, Call Settings, Blocked Numbers, and add them manually. The exact path varies by phone model and carrier.
Through your carrier's website: If you want to block many numbers or manage blocks from a computer, log into your carrier's account online. Most carriers (Verizon, AT&T, T-Mobile, and others) have a Call Filter or Call Block tool in their account settings. Some carriers charge a small monthly fee for advanced blocking features, though basic blocking is usually free.
What happens when you block a number
When you block an incoming number, that caller does not get a message saying you blocked them. They hear a standard message — usually "the call cannot be completed as dialed" or "this number is no longer in service" — which is the same message they would hear if your number were actually disconnected. They cannot tell the difference.
The blocked call does not show up in your phone's call log or notification center. If the blocked caller leaves a voicemail, it goes to a separate "Blocked Messages" folder that you can check if you want to, but you will not be notified about it.
If someone you blocked texts you, the text still arrives on your phone — blocking only stops calls, not messages. To block texts as well, you usually have to block the contact in your phone's Contacts app or use your carrier's messaging filter.
Calls that cannot be blocked
Emergency services (911) will always reach you, even if you have blocked the number. Your carrier's own messages — like alerts about your bill or service changes — usually cannot be blocked because they come from the carrier's system, not a regular phone number.
Some callers can pay to unblock their caller ID, which means their number will show up on your phone even if they are calling from a blocked number. This is rare and usually only available to businesses and government agencies. If you see a call from a number you blocked, it may be because the caller paid to unblock their ID.
Spam calls that spoof numbers (pretend to be from a local number or a business) cannot be permanently blocked because each call comes from a different number. For these, use your carrier's spam filter or a third-party app like Nomorobo or RoboKiller.
Why blocking your outgoing number can backfire
Many businesses, government offices, and hospitals screen out blocked calls because they assume they are spam. If you call your doctor's office, a bank, or a government agency with your number blocked, they may not answer or may hang up when ready.
If you need to call a business or official number, unblock your caller ID first. If you are calling a personal contact and want privacy, blocking your number is fine — but be aware that some people have their phones set to reject blocked calls, so they may not receive your call at all.
Frequently Asked Questions
Can someone find out my real number if I block it?
No. When you block your number using *67 or your phone's settings, the recipient cannot see your number or call you back at that number. However, if you leave a voicemail, some voicemail systems may record your number in the system even if it was blocked on the call itself — this depends on your carrier.
If I block someone, can they text me?
Yes. Blocking a number stops calls and voicemails from that person, but text messages still come through. To block texts as well, you need to block the contact in your phone's Contacts app or use your carrier's messaging filter, which is a separate setting from call blocking.
What is the difference between blocking a number and deleting a contact?
Deleting a contact just removes their name and information from your phone — they can still call you and you will see their number. Blocking a number stops their calls from reaching you at all. You can block a number without having it saved as a contact.
Does the person I blocked know I blocked them?
No. They hear a standard message that sounds like your number is disconnected or unavailable. They have no way to know whether you blocked them, whether your phone is off, or whether the number is actually out of service.
Can I block all unknown numbers at once?
Most phones have a "Silence Unknown Callers" or "Block Unknown Callers" setting that sends calls from numbers not in your contacts to voicemail. On iPhone, go to Settings, Phone, Silence Unknown Callers. On Android, go to Settings, Call Settings, and look for Block Unknown or similar. This does not block specific numbers — it blocks all callers whose numbers are not saved in your contacts.